SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e596f99ed0ba14926e1b43a72149b931b2045dfeb53fa2b383b0629e673b4e43' 
  AND token = 'R4jPoR8jxHwyGGVukgrH93hJ9D76spCCoobExNfwvKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}